The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An aircraft is moved by several turbojet engines each housed in a nacelle also housing a set of related actuating devices connected to its operation and performing various functions, when the turbojet engine is operating or stopped. These related actuating devices may in particular comprise a mechanical thrust reverser actuating system.
A nacelle generally has a tubular structure including an air intake in front of the turbojet engine, a middle section designed to surround a fan of the turbojet engine, a rear section housing thrust reverser means and designed to surround the combustion chamber of the turbojet engine, and generally ends with a jet nozzle whereof the outlet is situated downstream of the turbojet engine (so-called primary nozzle).
Modern nacelles are often designed to house a dual flow turbojet engine capable of generating, by means of the rotating fan blades, a hot air flow (also called primary flow) coming from the combustion chamber of the turbojet engine.
A nacelle generally includes an outer structure, called outer fixed structure (OFS), that defines, with a concentric inner structure of the rear section, called inner fixed structure (IFS), surrounding the structure of the turbojet engine strictly speaking behind the fan, an annular flow channel, also called secondary tunnel, aiming to channel a flow of cold air, called secondary flow, that circulates outside the turbojet engine.
Around the turbojet engine, the inner structure delimits a compartment and ventilation areas, the primary purpose of which is to refresh the air circulating between the IFS and the engine.
The inner structure and the jet nozzle delimit an outlet cross-section of the fan of the engine compartment.
Several cool air sources (taken from the secondary flow) supply the ventilation compartment, circulate along the turbojet engine, where they heat up before being discharged through the ventilation outlet.
In general, the ventilation inlet and outlet cross-sections are sized so as to ensure acceptable ventilation and pressure in the ventilation compartment along the turbojet engine.
Document WO 2009/024660 describes such a system for regulating the ventilation air and the pressure in the ventilation compartment. The described system also makes it possible to accommodate certain deformations of the turbojet engine during flight.
More specifically, document WO 2009/024660 describes a turbojet engine nacelle, comprising a rear section having an inner structure designed to surround a rear part of an engine compartment and to delimit, with a jet nozzle, a calibrated outlet cross-section of the ventilation of the engine compartment, using separating means arranged in the outlet cross-section, characterized in that the separating means can be broken down into rigid separating means designed to ensure constant separation, and compensating means designed so as to be able to adapt to the relative movements of the turbojet engine with respect to the nacelle.
It should, however, be noted that the turbojet engine is equipped with high pressure air discharge valves allowing it to regulate its performance. Generally, these discharge valves are situated inside the inner structure (IFS) and emerge inside the ventilation compartment.
Thus, in the case where one or more valves discharged in that ventilation compartment for certain flight cases, a major overpressure results that must be absorbed and regulated.
Another case of accidental overpressure may also be a burst duct incident of the turbojet engine.
Furthermore, these overpressures cause irregular loads of the inner structure that work in fatigue. It may also result in deformations of said inner structure and, consequently, a disruption of the flow of the air flow to the outside of the nacelle amounting to losses in aerodynamic efficiency.
It has appeared that the current solutions do not account for these discharge valves, and there is therefore a need for a solution making it possible to better account for these additional constraints.
More specifically, the current solutions do not allow active management of the ventilation outlet.